1. Field of the Invention
Applicant's invention relates to endoscopy and to instruments and methodologies that are useful in intubation procedures.
2. Background Information
Endotracheal intubation is the process by which a tube is inserted into the trachea of an individual who requires assistance in breathing. The need for intubation often arises from a cardiac and/or pulmonary arrest, or from trauma when the patient is unable to breath without outside intervention. Alternatively, elective intubation may be involved in preparing a patient for surgery under general anesthesia when the capacity for independent breathing may be interrupted. Over 10 million intubations are performed annually in the United States in approximately 6100 hospitals and 4000 ambulatory patient care facilities.
Intubation is a standard procedure for obtaining an artificial airway, but it can be difficult for the medical professional, and potentially dangerous for the patient. Properly negotiating the anatomy of the oropharynx and the larynx to ultimately place a tube in the trachea requires that the tube pass through the vocal cords, which are not always visible at the time of intubation. Thus intubation is often a partially blind procedure that relies on imperfect and indirect methods for confirming proper tube placement.
A Laryngoscope is an instrument designed and taught to be held with the left hand during intubation. It is used to divert the patient's tongue, epiglottis and other structures, and thereby enabling visualization of the vocal cords. However, often even with the Laryngoscope in an optimal position, the vocal cords cannot be visualized due to a variety of reasons, including the presence of a small mouth opening, an inability to optimally position the head and/or neck due to trauma or other reasons, or to an anterior position of the larynx. With any of these or similar conditions, placement of the tube becomes a partially blind procedure.
The most critical phase of intubation occurs when the tube is seen passing between the vocal cords and into the trachea. Without actually viewing the tube passing between the vocal cords and into the trachea, an intubation becomes more difficult or even impossible. Therefore, absolute certainty of the proper placement of the tube in the trachea is a fundamental requirement of every intubation.
If the vocal cords are visualized and the tube is seen passing through the vocal cords and into the trachea, post-intubation methods for verifying proper tube placement are still required to assure that the tube is in proper position within the trachea—2 cm above the tracheal bifurcation, or carina. The best confirmation method is to directly see the tube pass between the vocal cords and into the trachea, and the ideal time to know that this has occurred is during intubation itself. Properly securing the airway is the vital first step in patient resuscitation and in maintaining life support.
Methods for confirming proper tube placement, and thereby excluding an improper esophageal intubation (which precludes adequate oxygen delivery and carbon dioxide removal in the patient), an improper bronchial intubation (which blocks gas flow to the opposite lung), or improperly placed endotracheal intubation, are not always reliable because they are not sensitive or specific enough to provide absolute certainty of proper tube placement. Even the most reliable methods currently used for verifying properly placed tracheal intubation are indirect, take place after intubation, are undesirably time consuming, unnecessarily expensive, and can be associated with undesirable effects (e.g., radiation exposure in the case of chest x-ray confirmation).
The most commonly employed indicators for proper placement of a tube involves:    1) Auscultation, i.e., listening to the chest for breath sounds when the patient is ventilated. Such apparent indication of proper tube placement has, however, been reported in cases that ultimately turned out to involve esophageal intubations.    2) Pulse oximetry. An unrecognized or delayed recognition of an esophageal intubation will only eventually cause a decrease in oxygen saturation—several minutes may elapse before this occurs. In one study, detection of an esophageal intubation required 5 or more minutes in 97% of the cases.    3) Capnography detects carbon dioxide emission from the tube, which indicates that the tube is in communication with the patient's lungs and is serving as a conduit for exhausting the carbon dioxide of respiration. This method involves the expense of a disposable carbon dioxide sensor and is susceptible to both false positive and false negative results under certain circumstances that relate to the patient's gastric state and/or cardiac function at the time of intubation.    4) Chest radiography. X-ray verification involves radiation exposure, which should be avoided when non-radiation methods are equally or more efficacious. Besides, radiographic verification of proper tube placement is time consuming, adds expense and is not absolutely reliable. Also, since in surgical patients the x-ray is taken after surgery in the post-anesthesia care unit or in the intensive care unit, determination of an improper endotracheal intubation can be delayed.
In light of the limitations of indirect, post-intubation indication of proper tube placement, it is best to insure that one achieves visualization of the vocal cords for insuring certain passage of the endotracheal tube therethrough.
Presently, quite elaborate means are employed to achieve endotracheal tube passage visualization. As will be explained in more detail later, this is the result of those in the art failing to recognize that changes to existing Laryngoscope designs can more effectively, efficiently and inexpensively solve the problem, than can the to-be-described, elaborate methods.
An endoscope presents an image of a remote site within the body to a viewer outside the body. This can be achieved using a number of methods, including direct imaging of the site through conventional optical elements in a rigid array, indirect relay of the image through a flexible image conduit using conventional optics at either end, or by forming an image on an electronic imaging device proximal to the site and displayed on a monitor, or other viewing device.
Fiberoptic-based endoscopes are used by some to visualize proper endotracheal tube placement. No existing endoscope allows for simultaneous adjustment to the airway anatomy during an intubation with continuous visual confirmation of proper tube insertion. Two fiberoptic-aided intubation methods are presently available: 1) the “tube-first” approach, and 2) the “endoscope-first” approach.
In the tube-first approach to fiberoptic intubation, an intubating airway (a plastic device that is placed temporarily in the patient's mouth [oropharynx] to guide a tube generally toward its intended target) is placed in the oropharynx, and a tube is then inserted into the passageway of the intubating airway. While a second person supports the tube, which is now held in position by the intubating airway, an adult bronchoscope is inserted into the tube and advanced (using both hands) through the tube, through the vocal cords, and into the trachea. Using the endoscope insertion cord as a guide wire, the second person then blindly advances the tube over the endoscope and hopefully into the trachea. The bronchoscope, which served the purpose of a passive guide wire, is then withdrawn while holding the tube in place, after checking for proper tube placement.
The tube-first approach to fiberoptic intubation using presently available equipment has limitations. The stiffer tube can easily displace the thin, pliable insertion cord of currently available endoscopes. Thus, the tube may not follow the intended path of the correctly-placed endoscope insertion cord into the trachea, but rather the tube may drag the insertion cord along a path along a path of least resistance into the esophagus.
An uncommon but difficult situation may arise as the endoscope is being advanced through the tube. As the distal tip of the endoscope nears the distal end of the tube, the endoscope tip may (and often does) pass through the Murphy's eye of the tube. The Murphy's eye, an opening in the side of the tube (or side port) 1 cm. from the tip, prevents complete occlusion of the tube if the opening becomes blocked. If the endoscope tip is unintentionally passed through the Murphy's eye during an intubation, withdrawing the tube may be impossible without injury to the patient. Maneuverability of the tube/endoscope complex is severely diminished. (As stated earlier, this Murphy's eye entanglement problem is rare; however, such problems would be non-existent with the proposed endoscope.)
In the endoscope-first approach, the medical professional first attempts to direct the endoscope, with a tube pre-loaded back on the most proximal portion of the endoscope insertion cord, into the trachea, after which the tube is, as described before, advanced over the endoscope, using the endoscope essentially as a guide wire, into the trachea. This approach reduces the likelihood of advancing the endoscope tip through the Murphy's eye, but retains the limitations of the endoscope to act as a guide wire. The existing endoscope insertion cords are often too flexible to reliably guide a tube to an intended position in the trachea. This is true, in part, because as the tube is advanced over the endoscope, the endoscope passively (and blindly to the operator) guides the advancing tube to its intended endotracheal position, often through unyielding airway anatomy that can, combined with the forces used to advance the tube, divert the tube away from the intended path with an overall force that is greater than the passive guide wire can resist.
There are other significant limitations of the current fiberoptic technology. For example, in both the tube-first approach and the phases of the endoscope-first approach, during which the tube is advanced over the endoscope, the distal margins of the tube may get caught on laryngeal anatomy and thus be incapable of being advanced into the trachea. Also, during any phase of an intubation where one attempts to advance a tube over an already-placed endoscope, there may be a tendency to pull the endoscope back from its proper position as the tube is advanced, thereby resulting in an esophageal intubation or other complications. This is true particularly because two practitioners are required for currently practiced fiberoptic intubation procedures, one of whom must be well trained and experienced in bronchoscopy. Perfect coordination between the two, or detecting the lack thereof in the often hectic environment of a difficult intubation is not always possible.
The need for two practitioners for fiberoptic intubation procedures arises, in part, from the fact that currently available endoscopes and tubes are not specifically designed to be used together. The length of presently available endoscopes far exceeds that of the tubes with which they may be used, making their operation more complex. They lack a stylet function which would be helpful in manipulating the endoscope and tube as one unit and ensuring that the endoscope, and the loaded tube, will follow a desired path shape that ends in the proper location within the trachea.
In lieu of such complex approaches to achieving visualization in difficult airway situations, the present invention is of an improved Laryngoscope which in the vast majority of cases will obviate the need for such approaches.
There are many advantages of the proposed, improved Laryngoscope. Medical professionals and patients would benefit from a single device that addresses the deficiencies of equipment currently used to perform intubation, and requires only using standard hand motions used by most practitioners who perform routine intubations in direct laryngoscopy. Another primary advantage is that such an improved instrument would substantially simplify intubation and significantly increase the probability that each intubation will proceed properly, swiftly, and safely.
The benefit of the Laryngoscope design set forth herein derives from its enhanced ability to facilitate vocal chord visualization. This, in turn, arises from subtle, but highly significant contours and relative orientations of portions of the instrument.
In contrast to present Laryngoscope designs, the proposed Laryngoscope, far better than existing such instruments, displaces tissues which otherwise in most cases obscures visualization of the vocal chords, provides a “mechanical advantage” with respect to such displacement relative to wrist movement by the person conducting the intubation, whereby no observable, additional effort is required, nor difficulty is involved in utilizing the instrument's beneficial features and produced results, and protects the patient's teeth from damage which would otherwise be likely through use of conventional Laryngoscopes in achieving, or even attempting to achieve similar results.
The Laryngoscope of the present inventors' design involves a lobe, or distal enlargement, at the instrument's insertion end terminus. The size, shape and orientation of this lobe, relative to the instrument's handle and blade portions, facilitates a lifting and displacement of a patient's tongue during the intubation in a way not previously attainable with existing instruments, and in particular with such ease as is typical for use of the instrument of the present invention. The contours and relative orientations of the instrument's blade and handle portions, combined with the distal lobe, renders its optima use with minimal effort for even the moderately trained professional, while protecting the patient's teeth from Laryngoscope damage.